The present invention relates to an electronic circuit module retainer apparatus and more particularly to means for not only retaining a module in an enclosure but also providing adequate heat transfer between a module and a heat exchanger enclosure.
In the design of electronic equipment for use in severe environments such as in aircraft and military applications, the method of blowing air over or around electronic modules is often not satisfactory. Conduction cooling of electronic modules via liquid or air cooled heat exchanger enclosures is gaining acceptance for use in military applications.
Adequate structural integrity and heat transfer of an electronic module depends on a steady, low resistance contact between a module heat sink or thermal frame and a heat exchanger enclosure. Various types of module retainers attached to the thermal frame of a module and suitably fastened and torqued into an enclosure or housing have been used. One type of retainer referred to as a "Card-LOK" retainer by its manufacturer Calmark Corp. of San Gabriel, CA provides an efficient heat sink means; it comprises a screw passing through a front wedge, a center body section and a rear wedge having a threaded hole. The screw actuates wedge shape pieces, locks a module in place and provides maximum contact between thermal paths on a module and the heat sink surface of an enclosure. Insertion of a module into an enclosure using this wedge type retainer requires the retainer pieces to be in a loosened condition. However, under-loosening can cause a jam-up between the module and enclosure on insertion and over-loosening can cause one of the end wedges to rotate and prevent insertion; both conditions cause a hang-up between module and enclosure. Mounting a wedge-type of module retainer inside an enclosure rather than on the module greatly increases the above problems and can result in severe damage to an electronic assembly. The present invention incorporates anti-hang-up, non-rotation, and fool-proof module insertion features to eliminate the problems experienced with the prior art wedge type retainer.